The present invention relates to a rotary laser irradiating system for forming a reference point, a reference line and a reference plane for measurement by projecting laser beam or by reciprocally scanning and rotating laser beam, and, in particular, for simultaneously forming a tilt setting plane tilted at a predetermined angle with respect to a horizontal reference plane in addition to the horizontal reference plane. The invention also relates to a photodetection system for identifying a plurality of reference planes formed by the rotary laser irradiating system without erroneously recognizing the reference planes.
With the purpose of providing a horizontal reference level for a wide range, a rotary laser irradiating system is now used instead of an optical type leveling system.
In recent years, the rotary laser irradiating system has been used for the case where a line or a plane is formed according to the measurement in a height direction--in particular, according to a reference height. In the rotary laser irradiating system, laser beam is irradiated in a horizontal direction, or it is rotated or reciprocally scanned or stopped, and a rotary reference plane is formed or a partial reference line, a reference plane, and further, a reference line and a reference point are formed.
For example, it is used for forming a reference horizontal line for the purpose of positioning of window frames in interior finishing work, or for forming a reference horizontal plane with the purpose of ground filling or for forming graded soil surface in civil engineering and construction work. Further, the rotary laser irradiating system is also used for the setting of a reference point to determine tilting in case of construction of staircase, for example. There are also systems for forming a reference plane, which is tilted in one or two directions.
A conventional type rotary laser irradiating system for forming a tilted reference plane is disclosed in JP-A-6-26861. Brief description will be given now on this conventional type rotary laser irradiating system referring to FIG. 11.
At the center on the upper surface of a casing 1, a recessed portion 2 in shape of truncated cone is formed. A laser projector 3 is penetrating the center of the recessed portion 2 in a vertical direction, and the laser projector 3 is tiltably supported on the recessed portion 2 via a spherical seat 4. The head of the laser projector 3 has a pentagonal prism 9 and is acting as a rotator 5 which is freely rotated. The rotator 5 is rotated by a scanning motor 6 via a driving gear 7 and a scanning gear 8. Around the laser projector 3, two sets of tilting mechanisms 10 (only one is shown in the figure) are provided. The tilting mechanism 10 comprises a tilting motor 11, a tilting screw 12, and a tilting nut 13, and the tilting motor 11 rotates the tilting screw 12 via a driving gear 14 and a tilting gear 15. The tilting nut 13 is connected to the laser projector 3 via a tilting arm 16. When the tilting motor 11 is driven, the tilting nut 13 is moved up or down, and when the nut is moved up or down, the laser projector 3 is tilted.
At the middle of the laser projector 3, there are provided a fixed tilt sensor 18 positioned in parallel to the tilting arm 16 and a fixed tilt sensor 19 positioned perpendicularly to the fixed tilt sensor 18. At the lower end of the laser projector 3, a flange 20 is fixedly mounted. On a pivot pin 21 erected on the flange 20, an L-shaped tilt base 22 is pivotally supported on the corner. Two edges of the tilt base 22 running perpendicularly to each other are connected to two sets of tilt setting mechanisms 25 (only one is shown in the figure) respectively. On the tilting base 22, an angle setting tilt sensor 29 is arranged in the same direction as the fixed tilt sensor 18, and an angle setting tilt sensor 30 is arranged in the same direction as the fixed tilt sensor 19.
The tilt setting mechanism 25 comprises a tilt angle setting motor 26, a tilt setting screw 27 to be rotated by the tilt angle setting motor 26, and a nut block 28 screwed on the tilt setting screw 27, and one end of the tilting base 22 is engaged with the nut block 28. When the tilt angle setting motor 26 is driven, the nut block 28 is moved up or down via the tilt setting screw 27, and the tilting base 22 is tilted.
Inside the laser projector 3, a projection optical system (not shown) is incorporated, which comprises a laser light emitting unit (not shown) and a collimator lens to turn the laser beams emitted from the laser light emitting unit to parallel beams. The laser beams from the projection optical system are deflected to the horizontal direction by the pentagonal prism 9 and are projected through a projection window 31.
The setting of tilt angle is performed by the tilt setting mechanism 25. With the fixed tilt sensors 18 and 19 indicating horizontal position, the tilt angle setting motor 26 is driven, and the tilt setting screw 27 is rotated to move the nut block 28 up or down, and the tilting base 22 is tilted by the same angle .theta. as the setting angle in a direction opposite to the setting angle. Tilt angle of the tilting base 22 is detected by an encoder, etc. which is connected to the tilt angle setting motor 26.
Next, the laser projector 3 is tilted in a tilting direction by the tilting mechanism 10. When the tilting base 22 detects horizontal position, the angle of the laser projector 3 is at the setting tilt angle. With the tilt angle of the laser projector 3 set in the setting condition, laser beams are irradiated in the horizontal direction from the laser projector 3 via the pentagonal prism 9, and the rotator 5 is rotated or reciprocally scanned within a predetermined angle, and a tilted reference plane is formed.
In order to form a tilted reference plane in the conventional type rotary laser irradiating system as described above, it is necessary to support the laser projector 3 so that it can be freely tilted and also to have two sets of tilt setting mechanisms to tilt in two directions. Also, it is necessary to have an angle setting tilt sensor 29 in the same direction as the fixed tilt sensor 18. Further, a control circuit is required for driving and controlling the two sets of tilt setting mechanisms. This makes the system more complicated and requires higher manufacturing cost. Further, in the conventional type rotary laser irradiating system as described above, only one reference plane can be formed. Therefore, it is not possible to form a tilted reference plane with respect to the horizontal reference plane at the same time, and relative relation between the horizontal reference and the tilted reference plane or the relative relation between two tilted reference planes with different tilt angles cannot be determined.